Ahsoka's Backstory Suffers Retcon in Tales of the Jedi, Leaving Fans Pissed Off
Star Wars is one of the oldest examples of a shared universe, containing works by many authors in different media.
Star Wars is also a classic example of continuity problems within a shared universe, with authors disregarding and contradicting each other's works. When, after the Disney acquisition, the old Star Wars Expanded Universe was renamed "Legends" and effectively scrapped in favor of the new Disney canon, the fans were promised that the problem of contradictory canon is going to be fixed once and for all, in fact, that was one of the justifications for the scrapping.
The promise did not come true, and the latest example of that came with Tales of the Jedi animated mini-series, created by Dave Filoni, which just dropped on Disney Plus. Its final episode covers what happened to Ahsoka Tano between the rise of the Empire, and her joining the Rebellion and taking the role of Fulcrum.
However, the same ground already was covered by 2016 Ahsoka book, written by E. K. Johnston. It is not the matter of some obscure canon trivia from something published a couple of decades ago, but of a book covering the exact same character and part of the timeline.
Even Dave Filoni himself has previously claimed to have worked with E. K. Johnston on the story. And indeed the episode goes in close parallel with the book.
But there are numerous divergences, just serious enough for the episode to become something other than the compressed adaptation of the book. Most crucially, invading Imperial forces are replaced with just a single Inquisitor, so instead of being gradually forced to first join the struggle against their oppression, while still maintaining her secrets, and then to reveal her Force abilities for the sake saving her allies, Ahsoka goes back from self-imposed retirement in the span of one scene, and her use of the Force to save someone is completely recontextualized into an act which only accidentally led to the reveal of her true identity.
Now, sure, a 14-minutes episode is not enough to wholly adapt a large part of a book, but there is a difference between pragmatic compression, and changing things to the point of irreconcilable differences, seemingly just for the sake of changing them. Many of the fans devoted enough to read the book in the first place were not pleased.
"The episode was very clearly based on the novel but didn't follow it at all. It seems like Filoni tried rushing an entire novel's plot into 20 minutes and that's what we got. I enjoyed the episode but it's sad they just retconned majority of the plot of the book." – u/fresh_soup
If this trend of unnecessary continuity changes is to continue, the predictable outcome would be diminishing interest in the book part of the franchise.